Holley 4150 dripping fuel from primary discharge nozzle?

By "discharge nozzle", are you referring to the accelerator pump nozzles? If so, you may be missing the little "needles" that go under the discharge nozzles. These keep the vacuum from pulling fuel out of them. At idle, they plug the passage. But the accelerator pump pressure simply pushes them up and allows fuel to squirt out when you mash the pedal.

https://www.holley.com/products/fue...components/accelerator_pump_parts/parts/121-5

Otherwise, you may be referring to the "booster".